The 20-year-old centre-back has recently emerged as one of the Championship’s finest young players after establishing himself as a first-team regular at The City Ground.
Red Devils chief David Moyes has been alerted by this, and is making initial moves to put the wheels in motion for an end of season swoop.
It is understood that scouts from United will be at attendance for all games that Lascelles plays between now and the end of the season
Although the club see the youngster as a potential purchase, it is thought that they are desperate to judge him in more depth to assess whether of not he is ready to make the move up to the top tier.
Their decision is somewhat justified, with Forest said to be demanding around £15m for the defender who only made his senior debut in 2012
Liverpool and Everton have also been linked with Lacelles, while it has emerged that Arsenal made approaches for his signature when he was just 17.